From: Selamet Aydogdu <selamet.aydogdu_at_sbszh.ch>
Date: Wed, 1 Feb 2006 11:32:07 +0100

Hi Rob

Thank your verry much for your detail infos. I have yet i hope a last
question:
On witch samplerating and hz you can't hear definitly the different between
a Sound on a CD and sound on an MP3-File?
Somebody thinks, that a compression with 224 kbps, 44100hz, VCR-Level 4 it's
sufficient to reach the CD-Quality.

Some tests and knowhow can be verry interesting.

Greetings
Selamet

> -----Ursprüngliche Nachricht-----
> Von: rockbox-bounces_at_cool.haxx.se
> [mailto:rockbox-bounces_at_cool.haxx.se] Im Auftrag von rob powell
> Gesendet: Mittwoch, 1. Februar 2006 11:11
> An: Rockbox
> Betreff: RE: Question about CD-Quality and MP3
>
>
> Hi,
>
> Not sure I understand the question entirely, but here's some help.
> Hopefully it'll be of use to others too.
>
> These comments are obviously not all-encompassing, but they
> do to gain an
> understanding. There are 2 elements to the quality of a
> digital audio file,
> whether it be MP3, Ogg, or whatever. Sample frequency and bit rate.
>
> First, professionally produced audio CD's are always sampled at 48KHZ,
> whereas most MP3's and minidisks tend to be sampled at 44KHZ.
> Second is the
> bit-rate, not so critical as the sampling rate, but still
> important. Most
> MP3's are recorded at 128KBPS, (kilobits per second), though
> of course you
> can record at whatever value you want, provided your MP3
> player will support
> it). I for example record books at 48KBPS, 22K sampling
> rate, and mono.
>
> It's generally agreed however that to obtain CD quality, you
> need to be
> recording MP3's and any other audio format for that matter at
> 192KBPS. For
> reasons that I'll go on to explain, it's not actual CD
> quality, but it's
> recognised to be audibly very close, and barely noticeable.
>
> There are basically 2 types of digital audio formats, lossie
> and lossless.
> Lossless create larger files, lossie ones smaller. .MP3 .ogg
> and .wma are
> examples of lossie formats, .wav is a lossless format. The
> issue is not
> whether you loose anything by converting to MP3, but whether
> you'll notice
> what you loose on the equipment you're using for playback.
> 44KHZ and 128KBPS
> are generally recognised to provide an adequate level of playback for
> portable digital audio devices, and indeed I find that
> generally to be true:
> however when I connect the Archos or Iriver to my hifi
> system, I can hear
> the difference quite easily between the CD and the music on my player.
> Basically it's horses for courses.
>
> Inevitably however there's a trade-off between file size and
> quality. You
> don't actually need an audio book (speech) to be the same
> quality as your
> favourite album: so you can get away with lower bit-rates and sample
> frequencies, which mean smaller files, and less space on your
> MP3 player. I
> change the bit-rate and sample rate quite a bit, depending on what I'm
> recording. Old football matches recorded from AM don't need
> to be recorded
> at a high bit rate and sample frequency, as the bandwidth of
> AM limits the
> quality of the original. Well-recorded stereo radio dramas
> however benefit
> from higher recording quality.
>
> The generally accepted rule is, that the MP3 standard is good for many
> reasons, not least because all digital music players will
> play it. However
> Ogg Vorbis WMA and others have advantages. Ogg Vorbis files
> take up less
> space for the same sample and bit-rate size. It's also a more modern
> encoding standard, and therefore the quality of a file will
> be higher if an
> MP3 file and an Ogg Vorbis file of the same size are
> compared. However a
> .ogg file and an MP3 file recorded at the same bit-rate and
> the same sample
> rate will be of very similar quality. That's as I understand
> it, if I've
> got it wrong, I'm happy to take corrections: as I'm a bit hazy there.
>
> Gary, you might know more.
>
> I think that all the units that'll take rockbox are
> capable of reading
> files from 32 to 320KBPS, and with sample rates of 22 to 48KHZ.
>
> In short, the lower the bit rate and sample frequency, the
> smaller the file,
> but the poorer the playback quality.
>
> HTH,
>
> Rob
>
> -----Original Message-----
> From: rockbox-bounces_at_cool.haxx.se
> [mailto:rockbox-bounces_at_cool.haxx.se]On
> Behalf Of Selamet Aydogdu
> Sent: 01 February 2006 09:32
> To: rockbox_at_cool.haxx.se
> Subject: Question about CD-Quality and MP3
>
>
> Hello,
>
> I search some sources that describe the different about MP3
> and CD-Quality.
> If it's possible that you can hear the same sound in MP3,
> that exists too in
> CD-Quality? Whats about OGG?
>
> Greetings
> Selamet
>
>
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Received on 2006-02-01